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One-step synthesis of centimeter-size alpha-MoO3 with single crystallinity
摘要： By utilizing the convenient physical vapor deposition procedure, a simple and low-cost synthesis route is developed to fabricate high-quality orthorhombic MoO3 crystals with single crystallinity and significant size (bigger than 10mm×10 mm2). A combined characterization techniques of atomic force microscopy, X-ray photoelectron spectroscopy, synchrotron-based X-ray diffraction and Raman spectroscopy confirm the high quality of α-MoO3 crystal from the point view of both electronic and physical structures. Compared to previous reports in literature, we demonstrate herein a rather simplified one-step approach with only the MoO3 powder needed. In the end, corresponding electrochromic performance has also been been tested which reveals high transmittance and remarkable optical properties which may broadens the potential applications of MoO3 single crystal in nanosensors, nanoelectronics and so on.
关键词： GIXRD,XPS,single crystallinity,Physical Vapor Deposition,α-MoO3
更新于2025-11-21 11:24:58
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Deposition of Organosilicon-Plasma Coating onto Fine Graphite Micropowder with a Downstream Tubular PECVD Reactor
摘要： Fine graphite micropowder was processed in a downstream tubular reactor to perform a fast and homogeneous plasma-enhanced chemical vapor deposition of an organosilicon-plasma coating onto the powder surface. As a single process run results in the deposition of a non-continuous coating, consisting of a nanoparticle distribution, on the powder surface, the powder was repeatedly reprocessed until a continuous coating was obtained. The coating was imaged with focused ion-beam scanning electron microscopy and chemically characterized with Raman spectroscopy and X-ray photoelectron spectroscopy. The assessment of the powder flowability was also performed to investigate the roughness of the coated surface. The chemical characterization indicated that the coating is composed of amorphous hydrogenated silicon carbide with a little oxygen contamination.
关键词： PECVD,FIB-SEM,Micropowders,XPS
更新于2025-11-21 11:20:42
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Visible-Light Induced Photodegradation of Organic Contaminants in Water Using Fe3O4 Nanoparticles Modified Polypyrrole/Fly Ash Cenosphere Composite
摘要： Ternary nano-composites of polypyrrole/iron oxide/fly ash cenosphere (PPY/Fe3O4/FAC) were synthesized and used as magnetic photocatalyst. The synergistic effect of FAC, a buoyant carrier and polypyrrole, a conducting polymer enhanced the photocatalytic activity. Different composites were synthesized by varying the concentration of Fe3O4 and FAC to evaluate its effect on the photocatalytic properties of composites. The presence of Fe in Fe2+ and Fe3+ oxidation states at binding energies of 709.3 and 711.4 eV respectively was depicted by XPS curve. PPY/Fe3O4/FAC (1 : 3) composite showed the highest photocatalytic activity with rate constant (k) 0.0058 min–1. The removal efficiency of BPA was found to be around 75% and ~62% total organic content (TOC) was eliminated at optimized conditions from the solution. Transmission electron microscopy (TEM) showed the cluster morphology of the PPY/Fe3O4/FAC nano-composites with ~6–10 nm size of Fe3O4. X-ray diffraction studies elucidated the characteristic peaks of both PPY and Fe3O4 at 2θ ~ 20°–30°, and 26.04°, respectively in the composites which also confirmed the interaction of PPY with Fe3O4.
关键词： photo-degradation,polypyrrole,XPS,Fe3O4,fly ash cenosphere
更新于2025-11-21 11:18:25
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Electronic, electrical and magnetic behaviours of reduced graphene-oxide functionalized with silica coated gold nanoparticles
摘要： We have synthesized graphene-oxide (GO) by the modi?ed hummer's process and subsequently reduced it with gold-nanoparticles (Au-NPs) using silica coated colloidal Au-NPs and hydrazine monohydrate solutions to form r-GO:Au-NPs nanocomposites. We have studied the microstructure, electronic, electrical and magnetic properties of r-GO and r-GO:Au-NPs nanocomposites. We have observed from the Raman spectroscopy that the intensity of D-peak (disorder) gets reduced with respect to G (graphite-cluster) in r-GO:Au-NPs composites. The reduction of ID/IG ratio obtained from Raman spectra [r-GO: 1.22 → r-GO:(Au-NPs)4.88: 0.98] clearly indicates that the sp2-cluster is reduced in r-GO:Au-NPs nanocomposites. The reduction of sp2-cluster and/or enhancement of sp3-cluster is due to replacement of sp2-cluster by the Au-NPs. This observation also observed from the X-ray absorption near edge structure (XANES) spectroscopy, X-ray photoelectron spectroscopy (XPS) measurements that are consistence with reduction of conductivity as we observe from the current (I) - voltage (V) characteristics of the nanocomposites. Magnetic M-H hysteresis loops show the magnetization is enhanced in r-GO:Au-NPs nanocomposites. We believe that the reduction of conductivity and enhancement of magnetization of r-GO:Au nanocomposites would be most suitable for ferro-electro-magnetic materials for the memory storage device applications.
关键词： I-V,XANES,R-GO,M-H,XPS,R-GO:Au-NPs
更新于2025-11-14 17:03:37
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Photoluminescent behaviour of Ce3+ ions in mixed fluoride structures
摘要： Investigations were done to modify the photoluminescence (PL) spectra of a cerium (Ce3+) doped strontium fluoride (SrF2:Ce3+) phosphor for better sensitization for solar cell application. For optimum sensitization it is needed that Ce3+ emission overlaps with Lanthanide (Ln3+) ions’ excitation energy ranges. SrF2:Ce3+ emission, however, does not overlap well with different 4f-4f Ln3+ ions’ excitation ranges. The PL behavior of Ce3+ in Sr1-xMxF2:Ce3+ (where M = Ca, Ba, Mg, La) was therefore investigated. Noticeable changes were observed in the shape of the excitation and emission spectra of Ce3+. The Sr0.49Ba0.50Ce0.01F2 phosphor produced a significant red shift with a broad emission band. The excitation spectrum of this sample was blue shifted if compared to the singly doped sample.
关键词： fluoride structure,XPS,luminescence,Ce3+
更新于2025-11-14 15:28:36
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Direct Observation of Structural Evolution of Metal Chalcogenide in Electrocatalytic Water Oxidation
摘要： As one of the most remarkable oxygen evolution reaction (OER) electrocatalysts, metal chalcogenides have been intensively reported due to their high OER activities during the past few decades. It has been reported that electron-chemical conversion of metal chalcogenides into oxides/hydroxides would take place after OER. However, the transition mechanism of such unstable structures, as well as the real active sites and catalytic activity during OER for these electrocatalysts, has not been understood yet, which urgently needs a direct observation for the electrocatalytic water oxidation process, especially at nano or even angstrom scale. In this research, by employing advanced Cs-corrected transmission electron microscopy (TEM), a step by step oxidational evolution of amorphous electrocatalyst CoSx into crystallized CoOOH in OER has been in situ captured: irreversible conversion of CoSx to crystallized CoOOH is initiated on the surface of electrocatalysts with a morphology change via Co(OH)2 intermediate during OER measurement, where CoOOH is confirmed as the real active species. Besides, this transition process has also been confirmed by multiple applications of X-ray photoelectron spectroscopy (XPS), in situ Fourier-transform infrared spectroscopy (FTIR) and other ex situ technologies. Moreover, based on this discovery, a high-efficiency electrocatalyst of a nitrogen-doped graphene foam (NGF) coated by CoSx has been explored through a thorough structure transformation of CoOOH. We believe this in situ and in-depth observation of structural evolution in OER measurement can provide insights into the fundamental understanding of the mechanism for OER catalysts, thus enabling the more rational design of low-cost and high-efficient electrocatalysts for water splitting.
关键词： structural evolution,XPS,in situ TEM,water oxidation,cobalt chalcogenide
更新于2025-11-14 15:27:09
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Polycrystal Synthesis, Crystal Growth, Structure, and Optical Properties of AgGaGe <sub/><i> <i>n</i> </i> </sub> S <sub/> 2( <i> <i>n</i> </i> +1) </sub> ( <i>n</i> = 2, 3, 4, and 5) Single Crystals for Mid-IR Laser Applications
摘要： AgGaGenS2(n+1) crystal is a series of quaternary for mid-IR laser applications of nonlinear optical materials converting a 1.064 μm pump signal (Nd:YAG laser) to 4?11 μm laser output, but only AgGaGeS4 has attracted the most attention, remaining the other promising AgGaGenS2(n+1) crystal whose physicochemical properties can be modulated by n value. In this work, AgGaGenS2(n+1) (n = 2, 3, 4, and 5) polycrystals are synthesized by vapor transport and mechanical oscillation method with di?erent cooling processes. High-resolution X-ray di?raction analysis and re?nement have revealed that all the four compounds are crystallized in the noncentrosymmetric orthorhombic space group Fdd2, resulting in the excellent nonlinear optical property, and the distortion of tetrahedron with the variation of n value causes the discrepancy of physicochemical property. Besides, using the modi?ed Bridgman method, AgGaGenS2(n+1) single crystals with 15 mm diameter and 20?40 mm length have been grown. We have discussed the structure and composition of AgGaGenS2(n+1) by XPS spectra and analyzed the three kinds of vibration modes of tetrahedral clusters by the Raman spectra. The Hall measurement indicates that the AgGaGenS2(n+1) single crystals are p-type semiconductor, and the carrier concentration decreases with the increasing n value. All the transmittances of as-grown AgGaGenS2(n+1) samples exceeds 60% in the transparent range, especially the transmittance of AgGaGe2S6, is up to 70% at 1064 nm, and the band gap of as-grown crystal increases from 2.85 eV for AgGaGe2S6 to 2.92 eV for AgGaGe5S12. After a thermal annealing treatment, the absorptions at 2.9, 4, and 10 μm have been eliminated, and the band gap changed into the range of 2.89?2.96 eV.
关键词： Hall measurement,nonlinear optical materials,thermal annealing treatment,vapor transport,AgGaGenS2(n+1),Bridgman method,Raman spectra,mid-IR laser applications,XPS spectra,mechanical oscillation method
更新于2025-11-14 15:27:09
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Single process CVD growth of hBN/Graphene heterostructures on copper thin films
摘要： In this study, we have successfully grown hBN/graphene heterostructures on copper thin films using chemical vapor deposition in a single process. The first and most surprising result is that graphene grows underneath hBN and adjacent to the Cu film even though it is deposited second. This was determined from cross-sectional TEM analysis and XPS depth profiling, which chemically identified the relative positions of hBN and graphene. The effect of various growth conditions on graphene/hBN heterostructures was also studied. It was found that a pressure of 200 torr and a hydrogen flow rate of 200 sccm (;1 H2/N2) yielded the highest quality of graphene, with full surface coverage occurring after a growth time of 120 min. The resulting graphene films were found to be approximately 6–8 layers thick. The grain size of the nanocrystalline graphene was found to be 15–50 nm varying based on growth conditions.
关键词： XPS depth profiling,copper thin films,TEM analysis,hBN/graphene heterostructures,chemical vapor deposition
更新于2025-11-14 14:32:36
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Layer-by-layer MoS2:GO composite thin films for optoelectronics device applications
摘要： With reference of our previous report (Appl. Surf. Sci. 2018, ASAP), the molybdenum disulphide (MoS2) thin film were prepared by the dip-coating technique at different temperatures (4000C – 4500C) using methanolic solution of ammonium molybdate and ammonium thiocyanate that are used as bare-substrate for the deposition of graphene oxide (GO) thin films. For the deposition of graphene oxide (GO), commercially purchased GO (0.5 mg in 10 mL aqueous solution) was deposited by dip-coating technique on dip-deposited MoS2 thin film to make layer-by-layer MoS2:GO composite thin films and hence studied their electronic and electrical behaviours. The micro-structural and surface morphology were studied using Raman spectroscopy and field emission scanning electron microscopy, whereas optical band estimated from the optical absorption spectra. The electronic structure and their bonding properties were studied using x-ray photoelectron spectroscopy and the electrical behaviours were observed from the current-voltage (I-V) characteristic curve. The formation of different phases of MoS:GO thin films show an enhanced electronic and electrical performance due to their unique-structure and the synergetic effect of MoS2:GO nanosheets when compared to those of bare MoS2.
关键词： XPS Spectroscopy,Layer-by-layer MoS2:GO composite thin films,I-V curve
更新于2025-10-22 19:40:53
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The effects of multicharged ion irradiation on a polycarbonate surface
摘要： Polycarbonate targets were irradiated with multicharged ions of argon and oxygen with kinetic energies between 375 eV and 1 keV. Scanning electron microscopy (SEM) and x-ray photoelectron spectroscopy (XPS) analysis following the irradiations showed evidence of bond-breaking at the polycarbonate surface. The extent of the ion-induced damage indicates that the ion charge state enhances the damage well beyond that observed for similar, low flux singly charged ions. A qualitative comparison with a simple description of the radius of capture for the initial transfer of electrons between the ion and surface is used to understand the multicharged ion effects.
关键词： XPS,polycarbonate,Multicharged ions
更新于2025-09-23 15:23:52